Re: Obsidian Aqua, catechol staining developer
Quote:
Originally Posted by
Cor
Jay,
Could you give a starting point for Ilford PanF, expose box speed I guess, but process for how long at what temperature?
Thanks,
Cor
Hi Cor,
OA and PF+ is one of my favorite combinations. A good starting point is:
OA 1:500, 70F, 8:00, agitate first 30 seconds, and then ten seconds/ minute.
The above should provide a point of departure for your own testing.
John,
I'm happy to share my work with other photographers, and I hope you find something useful in it.
Re: Obsidian Aqua, catechol staining developer
Thanks Jay!
I'll report back (although it will be 35mm...:)..)), I just have to wait for sufficient light outside right now,
Best,
Cor
Re: Obsidian Aqua, catechol staining developer
Hi Cor,
If you shoot in flat light, you might want to increase development a little. I think you'll like this combination.
Re: Obsidian Aqua, catechol staining developer
Quote:
Anyone knows where you get catechol in Canada?
/gth
You can get catechol from Nymoc in Toronto. Email John Burrows: nymoc@bellnet.ca
Re: Obsidian Aqua, catechol staining developer
I finally got caught up on some other pressing projects and had time to shoot a scene on which to test Obsidian Aqua developer, and offer the following comments:
1. The "A" portion of the developer was easy to mix, metabisulfite and catechol in distilled water. Rather than make a stock "B" solution, I added enough sodium sulfite to water to make a 6.66% working solution into which I added the 1:500 dilution of developer.
2. Following Jay's recommendation I developed 4x5 FP4+ for 9 minutes at 70 F. I agitated for the first 30 seconds, then 10 seconds every 2 minutes.
3. I got a nice, easily printable negative. Good contrast, same stain as I am accustomed to with Pyrocat.
4. To attempt to ascertain any difference in sharpness, I made an enlargement of a section of the negative with lots of detail at the highest magnification my setup will allow (actually as large as my anatomy will allow; with my eye to the focus finder I could just barely reach up to the focusing knob.) It is roughly equivalent to a 20x24" enlargement.
5. I compared this enlargement to an identical enlargement of another negative of the same film, exposed at the same time, but developed in Pyrocat HD, using semi-stand agitation. Using a strong magnifier, I "think" the O.A. enlargement is nominally sharper. I intended to scan and post the enlargements but they are so close that I am sure any differences would not survive the scanning and uploading process. At any rate, I feel comfortable stating that the O.A. enlargement is no worse than equally as sharp as the Pyrocat enlargement, even with more aggresive agitation.
6. As sharp as this negative is, I wonder if it could be improved with a less aggressive agitation routine, such as 30 seconds initial agitation followed by 10 seconds of agitation at the 1/4, 1/2 and 3/4 points, or even 1/3 and 2/3. I intend to explore this idea in the near future.
Thanks again to Jay for providing this developer, and for his generosity in sharing it here.
Re: Obsidian Aqua, catechol staining developer
Thank you Jay for providing once again an alternative developer. Have to try it as soon as I can get all the ingredients. Btw have you noticed that your stated amount of carbonate is the number of the beast 666 maybe that's why your developer works so well :-)
Dominik
Re: Obsidian Aqua, catechol staining developer
Jay,
1. What is the shelf life of the Catechol compound by itself? Reason I ask because in Canada it needs to be shipped as a dangerous compound so I might as well get a fair amount while I am at it. In other words several years worth.
2. How much diluted solution is needed to develop a specific amount of film - as in film area per liter? Normailized to How many rolls 35 or 120 per liter or how many 4x5 sheets per liter etc. This estimate to be taken conservatively.... i.e assuming I would be fairly frivolous with its use - one shot type....
3. Also... has anyone used OA on X-ray film emulsions?
/gth
1 Attachment(s)
Re: Obsidian Aqua, catechol staining developer
Quote:
Originally Posted by
gth
3. Also... has anyone used OA on X-ray film emulsions?
Attachment 73238
I've used OA with quite a few sheets of X-ray film now, and all I have to say is I'm in love! With that interval agitation Jay talks about on the first page, 1,2,4,8, etc., I'm able to shoot Green Latitude X-ray film @ ASA 320. This is, of course, considering I'm not stripping the emulsion, scanning and contact printing works fine. Here's a link to all the images I've already shot with OA as the developer, including 4 infrared shots as well (also great with OA!).
http://www.flickr.com/photos/mat4226/tags/oa/
Re: Obsidian Aqua, catechol staining developer
Quote:
Originally Posted by
gth
3. Also... has anyone used OA on X-ray film emulsions?
/gth
I plan to test it soon with Kodak T-Mat Green Xray film, Mat Marrash (IIRC he is a LFF member too) already did it, check his flickr stream: http://flic.kr/p/bzD9iU
Re: Obsidian Aqua, catechol staining developer
Quote:
Originally Posted by
Jay DeFehr
Thanks for the correction, Claudio. Your pH calculation looks about right, too.
So, is it 0.666% sodium carbonate solution or 6.66%? How many grams of sodium carbonate in 1000ml water? Thanks.